MTASK2015 - A Multi-Task kernel (MT) for the Sharp PC-1500
© Christophe Gottheimer, 1992-1993-2015
Download zipped WAV, documentation, assembly sources and examples:
Download full documentation in PDF: mtask2015.pdf.
This is my own implementation of a small multi-task kernel (MT). I started to
develop it in 1992 when I was working on vxWorks targets. I feel very funny
to try to go out of the way in this small computer. This was of course
possible because the BASIC ROM was able to divert the interruptions. I read
an article in a french computer review speaking about a small example of this
diversion. I adapted it and after I developed several MT-kernels, with each
time more functionalities.
One of the last I developed, supports an access to the MT-kernel through the
BASIC instruction TASK. This was useful to "speak" with a task without calling
an assembly routine interface.
I stopped the development to start another, more complex: A small multi-
process operating system named MMPS
Several years ago, I recovered the tapes where the MT-kernel was saved, but
I was not able to reload it or to extract a binary. I still own my written
notes. Some weeks ago, finally, I succeed to extract the binary images with
some parts corrupted, but my notes helped me to rebuild a working kernel.
I also use this work to change or correct some kernel requests and add some
new ones like the timer.
The MT-kernel alone needs 2Kb, so it is very difficult to use it in PC-1500
without a memory module. A module of at least 4Kb (CE-151) or a PC-1500A is
highly recommended. For the images with the TASK instruction and the keyboard
driver, 2.8Kb is required. Special images for PC-1500A are provided, because
of the different memory scheme; with these images, the task structures are
stored into the dedicated ML area (&7F00..&7F82). Note that standard images
also work into the PC-1500A.
The keyboard driver needs to run with a ROM A02 or higher. If the function
PEEK &E2B9 answers 56, the machine has a good ROM. Else, the driver and the
TASK instruction will be not usable. CALLREGS works on all ROMs. The PC-1500A
always have to good ROM.
With this software, you will discover, as example, a small scheduler-reminder task
working in "background" to "remind" your tasks, rendez-vous, or alarms,
even if a BASIC program is running...
With this software, a new BASIC instruction TASK is available to perform the request to
the Mult-Task kernel:
TASK RUN entry,stack[,prio[,tid]];var
TASK END tid
TASK STOP tid
TASK CONT tid
TASK NEW prio[,tid]
TASK PAUSE delay
TASK LOCK lockid
TASK LOCK WAIT lockid
TASK UNLOCK lockid
TASK INPUT var$
TASK PRINT tid,var$
TASK PRINT WAIT tid,var$
TASK PRINT INPUT tid,var$
TASK GOTO [handler]
TASK ON eventid
TASK OFF eventid
TASK CALL eventid,tid
TASK TIME [delay]
TASK POKE CLS lockid,cntid
TASK POKE lockid,cntid
TASK PEEK lockid,cntid
TASK DIM queue,size
TASK READ WAIT var
TASK READ var
TASK DATA tid,var
If an error occurs will calling the MT-kernel with TASK, the normal error
handling is assumed. The BASIC will show "ERROR eee" where eee is the decimal
See more informations into the documentation.
Note: This version is still in pre-alpha release. It is not fully mature and bugs may be present.
Disclaimer: You use this code at your own risk. I
am not responsible for any damage or any data lost or corrupted by
using this software or by using the binary images created with this
software while running them on a Sharp PC-1500/A or TRS-80 PC-2. Be sure
to save your important data or programs before loading and running the
binary images. C.G.
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